1. Field of the Invention
This invention relates to apparatus for setting roller clearances in machines for folding paper and the like.
2. Description of the Prior Art
Apparatus for setting roller clearances are well known in the art. Several variations are available, all of which provide for pre-adjustment of roller clearances by manual adjustment of a coil spring for each thickness of paper to be folded and which are difficult to manipulate. The typical folding machine has pairs of rollers, in number at least 4 rollers and most machines have 6 rollers, each pair of rollers (one stationary and one movable) have fold plates associated therewith. The rollers must be set at clearances sufficient to permit paper of a selected thickness to pass therethrough for folding, but close enough to exert sufficient pressure to move the paper without mishap. The paper as it is folded into the brochure or other folded article is in increasing thicknesses between each consecutive set of rollers and fold plates and, accordingly, the clearances must be different between the respective sets of movable and stationary rollers as the brochure moves through the folding machine.
In a typical folding machine such as shown in the U.S. Pat. No. 3,021,134 to G. T. APPELL, a roller hanger bracket 12 is shown having an arm 30 which a threaded rod 38 is engaged, with a spring 48 engaged therewith and with a knurled seat 50 bearing on the spring 48, maintaining predetermined tension on arm 30, and which rod 38 is engaged in a bracket 60. The rod 38 can be rotated to put spring pressure on arm 30, but when rotated in the opposite direction to move arm 30 for a new thickness of paper, relieves the tension on arm 30. The spring 48 length must then be changed to provide the required pressure on arm 30 for the new paper thickness.
The U.S. Patent to STEFFENS, et al., No. 4,032,133, illustrates a method and apparatus for roller positioning, which the same type of resilient structure 80 with a threaded rod and extension 82 with the same limitations of setting the spring tension upon rotation of the rod for different thickness of paper to be folded.
With the apparatus as shown in U.S. Pat. Nos. 3,021,134 and 4,032,133, each paper and spring arm pressure clearance must be set by trial and error, and these clearances are not easily changed. With the apparatus of my invention, actual specimens of the paper to be folded in number corresponding to the folds at each set of rollers are used for setting the roller clearances, and the predetermined spring pressure on the roller arm does not normally require change for different thicknesses of paper. The apparatus is easy to use and does not suffer from the shortcomings of the prior available structures.